I have 3 sulcata tortoises, two of them are 2 mths old and the other is 6 or 7 mths old. The problem is they are all the same size. The 6 mth old is not growing, and I was wondering if there were any ideas why. He eats like a pig, he's active and healthy. We have them in a 90 gal aquarium with heat and UVB. We have timothy hay in there, as well as feeding veggies everyday. Plus soaking at least two times a week. Any ideas that might help?